THE EFFECT OF DIVISION OF THE BURNED GAS REGION FOR REALISTIC IN-CYLINDER NO PREDICTIONS -AN EXPERIMENTAL AND THERMODYNAMIC STUDY

摘要

This article reports the experimental and theoretical results for a spark ignition engine working with compressed natural gas as a fuel. The theoretical part of this work uses a zero-dimensional, multi-zone combustion model in order to predict engine performance and nitric oxide (NO). During combustion, 12 products are obtained by chemical equilibrium via Gibbs energy minimization method whereas nitric oxide formation is updated from chemical kinetic by the extended Zeldovich mechanism using exact derivation. The burning rate required as input to the model is expressed as a Wiebe function, fitted to experimentally derived burn rates. The model is validated against experimental data from a four-cylinder, four-stroke, SI gas engine (EF7) running with CNG fuel. The calculated values for pressure and nitric oxide emissions show good agreement with the experimental data.